Here's my guess: there's a parameter in CSV called "style" it depends on character class and eqiupped weapon. When user do some action,(move,attack,...) client sends to server a packet which contains that style code. This code is also being send to any other player in whom view range you currently is, so they can see your actions. I thunk that main trick is this: if you change that value in CSV file, server will accept it anyway but since that code isn't associated with particular action in other's people clinets (unless they also changed it to the same value) you won't appear on their screens (client simply "doesn't know" what kind of action to display)